we don't know whether there is a concisely describable objective function that we are the optimum of
I think Wei_Dai was trying to suggest an objective function beyond our ken.
Discounting other theories unjustifiably, or overusing a particular theory past it's explanation is one sin. Not understanding a theory is another however. I think that many people who draw such false conclusions still base them on a pretty clear understanding of the core of evolutionary theory, i.e. mutation, gene exchange, selection, reproduction.
I meant to say, is that feeling of "ooh, shiny!" not easily appreciable value in itself?
I understand that I am incorrect, my own self-doubt was not made sufficiently clear. I do not however agree with the fatalism that I perceive in the initial quote. To me it seems to suggest that understanding evolution is impossible. I guess this is not necessarily the appropriate place to look for information on evolutionary theory, but nonetheless I do not agree with the suggestion of unassailability of understanding, if that is what's going on.
This may be fatally sophomoric, but I really don't understand what is so particularly hard to understand about the theory of evolution. Differentiation, Inheritance, Mutation, and Fitness produce a feedback loop of increasing Fitness. The particulars of it's implementation on Earth are far more complicated, but the underlying theory is beautiful in it's elegance and simplicity.
The problem with flipping the coin is that it already asks you to make an uncomfortable judgement about the values of John and Lisa's lives. You have already said "Our lives' values are comparable enough to merit coin-flipping". Acting out of the view of the partner gives the sort of mutual plausibly deniability that allows you to both percieve that the partner values your more than themselves.
I imagine you intended to link to consilience the concept, not the book. Then again you may just be trying to be subtle.